A West-backed rebel military operation to topple Syrian president Bashar al-Assad under the supervision of Jordanian, Israeli and American forces has already begun according to French newspaper Le Figaro.

Citing unnamed military sources, the daily reported that the first troops trained by Washington and Amman officials were deployed in mid-August in the Deraa region.

A 300-strong group of Free Syrian Army (FSA) fighters crossed the border with Syria on 17 August, and were joined by another group two days later.

"According to military sources, the Americans, who don't want to put troops on Syrian soil or arm rebels who are in part controlled by radical Islamists, have quietly trained a bunch of handpicked FSA fighters in training camps set up at the Jordanian-Syrian border," the paper said.

Le Figaro believes the pressure mounted by the specially-trained FSA fighters prompted Assad to launch an alleged attack on the rebels on Wednesday, using toxic gas. In July, the Syrian president said in a public speech that the regime would never use those weapons "except for external aggression".

Progress over summer

Over the summer the special troops began fighting Syrian government forces in the south of the country, approaching the capital.

"Their thrust could now be perceived in the Ghouta region, where FSA fighters were already operating," said David Rigoulet-Roze, researcher at the French Institute of Strategic Analysis (Ifas). "However, their real power can make a difference on the outskirts of the Damascus fortress."

Ghouta was heavily hit by the alleged chemical attack on Wednesday, with reports suggesting over 1,000 people died.

According to experts, Washington plans to create a buffer zone or a no-fly area from the south of Syria to allow rebels to operate safely, until the balance of power changes. This was also the reason behind America's decision to send Patriot batteries and F16s to Jordan at the end of June.

US President Barack Obama revealed on Friday that the US left 700 combat-equipped troops in Jordan after a training exercise.

"This detachment that participated in the exercise and remained in Jordan includes Patriot missile systems, fighter aircraft, and related support, command, control, and communications personnel and systems," Obama said.

Chemical attack fall-out continues

Meanwhile the fall-out from Wednesday's massacre in Ghouta continues, with UN secretary-general Ban Ki-moon suggesting the alleged chemical weapons attack near Damascus "needs to be investigated without delay".

Earlier France said a "reaction with force" might be needed. However the Syrian government has described the allegations of chemical weapons' use as "illogical and fabricated".

Meanwhile, UN agencies say the number of children forced to flee Syria has reached one million. Russia has called on the Syrian government and the opposition to cooperate with UN chemical weapons inspectors to allow them to investigate the alleged chemical attack.